The present invention relates to a duplex opposite friction hinge and particularly a duplex opposite friction hinge adopted for use on notebook computers, computer screens or articles which have a lid for adjusting the extending angle.
The notebook computers or handheld computers now being widely used have a display screen connecting to the computer processor through an axle coupling means. When in use, the display screen is flipped and extended. When not in use, the display screen may be folded to the computer processor to become a smaller size to facilitate storing and carrying.
In order to improve the convenience of use, it is generally required that the axle coupling means be adjustable in a stepless manner and be extended and anchored at a desired angle. The most commonly used axle coupling means for connecting the display screen and the computer processor is hinge. Referring to FIG. 1, a conventional hinge includes an axle 1xe2x80x2 and a rotary member 2xe2x80x2 coupling with the axle 1xe2x80x2. When in use, applying a force on the rotary member 2xe2x80x2, the friction force between the axle 1xe2x80x2 and the rotary member 2xe2x80x2 may be used to control the folding angle. The turning relationship between the axle 1xe2x80x2 and the rotary member 2xe2x80x2 may be that the axle 1xe2x80x2 remains stationary while the rotary member 2xe2x80x2 is turned, or the rotary member 2xe2x80x2 remains stationary while the axle 1xe2x80x2 is turned. Either way, such a structure occurs a metal friction loss during turning. The single piece rotary member 2xe2x80x2 tends to occur metal fatigue after being turned reciprocally and repeatedly for a long period of time. As a result, the gap between the axle 1xe2x80x2 and the rotary member 2xe2x80x2 increases, and the display screen could become wobbling and cannot be anchored steadily when extended. In serious situations, the rotary member 2xe2x80x2 might even fracture. Moreover, to increase the strength of the rotary member 2xe2x80x2, the elasticity suffers and the impact of torque resulting from the dimension error becomes greater and adjustment of the hinge becomes difficult and service life of the hinge also suffers. On the other hand, reducing the strength of the rotary member 2xe2x80x2 may increase the elasticity, but metal fatigue is easier to take place and the torque decreases. Hence in practice it is difficult to achieve a proper balance between the strength and the elasticity of the rotary member 2xe2x80x2.
Therefore the primary object of the invention is to resolve the aforesaid disadvantages. The invention provides two rotary members coupling with the axle in the opposite directions. The fastening sections (where the force is applied) are located transversely on the center line of the axle so that the two rotary members can provide same amount of friction forces. Thus when the hinge is turned in different directions, no adjustment error occurs.